Congestive Heart Failure (CHF) is a common chronic condition and a leading cause of death, disability, and hospital costs in the elderly. Proven-effective treatments for CHF can reduce the burden of disease and prolong survival, but these treatments are under-utilized. Patient self-management can also improve functioning and survival, but patients are often unaware of ways to detect and prevent worsening of the condition, and are therefore unprepared to intervene or seek help to stop the progression of disease. Health plans and other providers are increasingly employing nurse-based disease management (DM) to overcome these barriers. To test the effectiveness of nurse management, we recently conducted two randomized controlled trials of nurse management versus usual care: One was conducted by investigators at Mount Sinai School of Medicine (MSSM) in East and Central Harlem, New York; the other by investigators for the Kaiser/Stanford Heart Failure Care Management (KSHFC) study in California. The nurses in each trial followed similar protocols that instructed them to work with the clinicians to optimize drug therapy according to evidence-based guidelines, and to counsel patients on diet and self-monitoring of symptoms on regularlyscheduled telephone calls. Although the interventions were similar, baseline patient characteristics were different and the two trials yielded disparate results. The MSSM trial enrolled younger, lower socioeconomic status minority patients, and those in the nurse arm maintained a significantly higher level of physical functioning and were hospitalized fewer times than those in the control group. The KSHFC participants were predominantly middle-class white patients, and there was no difference in functioning or hospitalizations between treatment arms. The purpose of the proposed study is to reanalyze data from these trials to explore why one DM trial worked and the other did not, and more generally, to explore what aspects of complex DM protocols contribute to their success. The specific aims are 1) to investigate how differences in patient characteristics at baseline contributed to the disparate results of the two trials, and 2) to discover which of the nurses' activities contributed most to maintaining patients' physical functioning and reducing hospitalizations. .